1. Field of the Invention
The present invention relates to an improvement of an observation apparatus such as an operation microscope or a slit lamp.
2. Description of the Related Art
An operation microscope as an observation apparatus as shown in FIG. 1 is known in the prior art. In FIG. 1, reference numeral 1 denotes a support post, 2 denotes a support arm, and 3 denotes a bracket for attaching an operation microscope which is mounted to the end portion of the support arm.
The support arm 2 is composed of an L-shaped arm 4 and an swinging arm 5. The L-shaped arm 4 is attached to the top end portion of the support arm 2 such that it can be horizontally rotated. The swinging arm 5 is biased upward by a spring provided in the inner portion thereof.
An arm 6 which is held so as to be horizontally rotatable and extends downward is provided to the end portion of the swinging arm 5. The bracket 3 is attached to the arm 6.
An operation microscope 10 is attached to the bracket 3. The operation microscope 10 has a body tube 11. An observation optical system is provided in the body tube 11. An eyepiece lens body tube 11xe2x80x2 is provided to the body tube 11.
The operation microscope 10 has, for example, an illumination optical system 12 and an observation optical system 13 as shown in FIG. 2. The illumination optical system 12 is composed of an illumination light source 14, a condenser lens 15, an illumination field stop 16, a collimator lens 17, and a prism 18. Reference symbol 18b denotes a reflection surface of the prism 18. Illumination light from the illumination light source 14 is guided to an objective lens 19 used common to the observation optical system 13 via the condenser lens 15, the illumination field stop 16, the collimator lens 17, and the prism 18. Then, it is guided to, for example, an eye fundus Er of an operating eye E so that the eye fundus Er is illuminated. Note that reference symbol Ea denotes a pupil of the operating eye, Eb denotes an iris, and Ec denotes a cornea.
The observation optical system 13 is composed of a right-eye observation optical system 13a and a left-eye observation optical system 13b as shown in FIG. 3. The right-eye observation optical system 13a includes a variable power lens system (zoom lens system) 20 composed of lenses 20a, 20b, 20c, a beam splitter 21, an imaging lens 22, an image erecting prism 23, an interpupillary distance adjustment prism 24, a field stop 25, and an eyepiece 26. Note that reference symbol 2a1 denotes an entrance pupil and 26a denotes an eye point.
Similarly, the left-eye observation optical system 13b includes a variable power lens system (zoom lens system) 30 composed of lenses 30a, 30b, 30c, a beam splitter 31, an imaging lens 32, an image erecting prism 33, an interpupillary distance adjustment prism 34, a field stop 35, and an eyepiece 36. Note that reference symbol 2b1 denotes entrance pupil and 36a denotes an eye point.
The reflected light from the eye fundus Er of the eye to be examined E is guided to an eye of an operator through optical members from the object lens 19 of both the observation optical systems 13a and 13b to the eyepieces 26 and 36 so that the operator observes the eye fundus Er. A portion of the reflected light from the eye fundus Er is split by the beam splitters 21 and 31 and guided to an auxiliary observation optical system 40 for an assistant operator and a TV image pickup system 50.
In FIG. 3, reference numerals 41 and 51 are imaging lenses, 42 and 52 are reflection mirrors, 43 denotes an eyepiece, and 53 denotes a TV camera. The TV camera 53 has a CCD image pickup element as an image receiving means 53a. 
As shown in FIG. 4, an exit pupil 18a of the illumination optical system 12 is disposed in proximity to observation paths 2a2 and 2b2 of both the observation optical systems 13a and 13b. In FIG. 4, reference symbol xe2x80x9cOxe2x80x9d denotes an optical axis of the objective lens 19, O1 denotes an observation optical axis of the left-eye observation optical system 13a, and O2 denotes an observation optical axis of the right-eye observation optical system.
By the way, there is a case where it is desired to observe an eye fundus and its vicinities using such a kind of operation microscope. In such a case, as shown in FIG. 5, optical members such as a prism or lens, contact prism or contact lens (hereinafter referred to as xe2x80x9coptical membersxe2x80x9d) 60 are held against the cornea Ec of the eye to be examined E, thereby observing a vicinity portion Erxe2x80x2 of the eye fundus Er. In FIG. 5, such optical members 60 having an apical angle xcex8 (for example, 45 degrees) are held against the cornea Ec.
Thus, when such optical members 60 are held against the cornea Ec, the optical axis xe2x80x9cOxe2x80x9d of the objective lens 19, an illumination optical axis Oxe2x80x2 of the illumination optical system 12, and the observation optical axes O1 and O2 of both the observation optical systems 13a and 13b are refracted so that the eye fundus vicinity portion Erxe2x80x2 of the eye fundus is observed. When the apical angle xcex8 of optical members 60 are varied as appropriate, an observation site of the eye fundus vicinity portion Erxe2x80x2 can be changed as appropriate.
However, when the eye fundus vicinity portion Erxe2x80x2 is observed using optical members 60, astigmatism and chromatic aberration are caused by a refraction and dispersion action of light. FIG. 6 is a schematic diagram of astigmatism in a state in which optical members 60 are not held against the operating eye E. The abscissa indicates the amount of defocus when a focusing position is assumed as an origin point and defocusing is made forward and backward. The ordinate indicates a size and a shape of a point image Q at positions corresponding to the respective amounts of defocus. When optical members 60 are not held against the cornea Ec, even if the amount of defocus become large relative to the focusing state, the point image Q is kept in substantially a circular shape. In contrast to this, FIG. 7 is a schematic diagram of astigmatism in a state in which optical members 60 are held against the operating eye. The abscissa indicates the amount of defocus when defocusing is caused forward and backward. The ordinate indicates a size and a shape of the point image at positions corresponding to the respective amounts of defocus.
When optical members 60 are held against the cornea Ec, the astigmatism is caused. That is, a position at which the point image Q becomes circular in shape is shifted from the focusing position and it shape transforms from a longitudinal elliptical shape to a transverse elliptical shape via a minimum circle as the focusing state is changed from a focusing position front side to a focusing position back side.
Also, FIG. 8 is a schematic diagram of astigmatism and chromatic aberration in a state in which optical members are not held against the operating eye. The abscissa indicates the amount of defocus when the focusing position is assumed as an origin point and defocusing is caused forward and backward. The ordinate indicates a size and a shape of the point image Q at positions corresponding to the respective amounts of defocus. When optical members 60 are not held against the cornea Ec, even if the amount of defocus become large relative to the focusing state, the point image Q is kept in substantially a circular shape. Also, almost no chromatic aberration whereby an image is separated among R, G, and B is observed. It is observed only slightly as the amount of defocus increases. Thus, almost no practical problem is caused in the case of the observation in the focusing position.
In contrast to this, FIG. 9 is a schematic diagram of astigmatism and chromatic aberration in a state in which optical members 60 are held against the operating eye Ec. The abscissa indicates the amount of defocus when the focusing position is assumed as an origin point and defocusing is made forward and backward. The ordinate indicates a size and a shape of the point image Q at positions corresponding to the respective amounts of defocus. When optical members 60 are held against the cornea Ec, the astigmatism is caused. That is, a position at which the point image Q becomes circular in shape is shifted from the focusing position and its shape transforms from a longitudinal elliptical shape to a transverse elliptical shape via a minimum circle as the focusing state is changed from a focusing position front side to a focusing position back side. In addition, simultaneously, chromatic aberration is caused by a refraction action of optical members 60 even in the focusing position. Here, the chromatic aberration is schematically indicated using three colors of R, G, and B. A color separation direction is a direction in which refractive power of optical members 60 acts, which is the ordinate direction in this example.
Thus, when the chromatic aberration is caused, as shown in FIG. 10, even if the astigmatism is removed, the chromatic aberration is left.
In the case where the astigmatism and the chromatic aberration are caused, when optical members 60 are held against the cornea Ec of the operating eye E and the eye fundus vicinity portion Erxe2x80x2 is observed, the eye fundus image appears as being distorted with color separation. Thus, a sharp image of the eye fundus vicinity portion Erxe2x80x2 cannot be viewed so that it is hard to operate the eye fundus vicinity portion Erxe2x80x2.
In particular, when operating an eye into which an intraocular lens (IOL) is implanted, the influences of the astigmatism and the chromatic aberration thereof become large. Thus, there is a problem that it is difficult to observe a sharp image of the eye fundus vicinity portion Erxe2x80x2.
Further, the astigmatism is caused also when optical members 60 are held against the cornea of the operating eye E and coagulation therapy of the eye fundus using laser light is conducted.
Therefore, a first object of the present invention is to provide an observation apparatus capable of removing astigmatism.
A second object of the present invention is to provide an observation apparatus capable of removing chromatic aberration.
A third object of the present invention is to provide an observation apparatus for conducting eye fundus therapy.
According to a first aspect of the present invention, there is provided an observation apparatus, which comprises a variable power lens system and an imaging lens located on an observation path of the observation optical system extending from an objective lens to an eyepiece, in which:
of the observation optical system, an observation optical system extending from the objective lens to the variable power lens system is an observation path for relaying as parallel light fluxes reflected light from an eye fundus of an operating eye to the variable power lens system; and
of the observation optical system, an observation optical system extending from the variable power lens system to the imaging lens is an observation path for relaying as parallel light fluxes the reflected light fluxes obtained through the variable power lens system to the imaging lens,
characterized in that an astigmatism canceling optical element is provided on the observation path of the observation optical system extending from the objective lens to the eyepiece, for canceling astigmatism power caused when optical members are held against the operating eye.
According to a second aspect of the present invention, there is provided an observation apparatus characterized in that the astigmatism canceling optical element is provided between the variable power lens system and the imaging lens.
According to a third aspect of the present invention, there is provided an observation apparatus characterized in that the astigmatism canceling optical element is provided between the objective lens and the variable power lens system.
According to a fourth aspect of the present invention, there is provided an observation apparatus characterized in that the astigmatism canceling optical element consists of a pair of variable cylindrical lenses that are rotatable relative to each other about an observation optical axis of the observation path, and further includes a correction lens for arbitrarily correcting the amount of positive or negative astigmatism.
According to a fifth aspect of the present invention, there is provided an observation apparatus comprising amount-of-astigmatism-correction automatic changing means capable of correcting astigmatism that changes according to observation magnifications, characterized in that the amount-of-astigmatism-correction automatic changing means includes variable cylindrical lens rotating means for rotating the variable cylindrical lenses, and the variable cylindrical lens rotating means rotates, in order to cancel the astigmatism, the variable cylindrical lenses relative to each other about the observation optical axis in accordance with an amount of astigmatism correction to thereby change power thereof.
According to a sixth aspect of the present invention, there is provided an observation apparatus characterized in that the observation optical system includes image receiving means for receiving reflected light from the eye fundus, the image receiving means being connected with an image processing device, and the amount-of-astigmatism-correction automatic changing means computes the amount of astigmatism correction by analyzing an eye fundus image received on the image receiving means by the image processing device and controls the variable cylindrical lens rotating means to rotate the variable cylindrical lenses in accordance with a computed result.
According to a seventh aspect of the present invention, there is provided an observation apparatus characterized in that:
the observation optical system includes:
a projection optical system for projecting a pattern image to the eye fundus through the objective lens; and
image receiving means for receiving reflected light from the eye fundus, which is connected with an image processing device; and
the amount-of-astigmatism-correction automatic changing means computes the amount of astigmatism correction by analyzing a pattern image received on the image receiving means by using the image processing device, and controls the variable cylindrical lens rotating means to rotate the variable cylindrical lenses in accordance with a computed result.
According to an eighth aspect of the present invention, there is provided an observation apparatus characterized in that:
the amount-of-astigmatism-correction automatic changing means includes a memory for storing the amounts of astigmatism correction corresponding to respective observation magnifications of a prism having a reference apical angle; and
the amount-of-astigmatism-correction automatic changing means corrects, after once determining the amount of correction corresponding to an observation magnification of optical members having an apical angle different from that of the prism having the reference apical angle, the amounts of correction corresponding to other observation magnifications in accordance with the amounts of correction stored in the memory.
According to a ninth aspect of the present invention, there is provided an observation apparatus characterized by comprising an achromatic optical element having power in a direction for canceling chromatic aberration caused when optical members are held against the operating eye, the achromatic optical element being provided between the variable power lens system and the imaging lens.
According to a tenth aspect of the present invention, there is provided an observation apparatus, which comprises a variable power lens system and an imaging lens located on an observation path of the observation optical system extending from an objective lens to an eyepiece, in which:
of the observation optical system, an observation optical system extending from the objective lens to the variable power lens system is an observation path for relaying as parallel light fluxes reflected light from an eye fundus of an operating eye to the variable power lens system; and
of the observation optical system, an observation optical system extending from the variable power lens system to the imaging lens is an observation path for relaying as parallel light fluxes the reflected light fluxes obtained through the variable power lens system to the imaging lens,
characterized in that an achromatic optical element is provided on the observation path of the observation optical system extending from the objective lens to the eyepiece, for canceling chromatic aberration caused when optical members are held against the operating eye.
According to an eleventh aspect of the present invention, there is provided an observation apparatus characterized in that the achromatic optical element is provided between the variable power lens system and the eyepiece.
According to a twelfth aspect of the present invention, there is provided an observation apparatus characterized in that the achromatic optical element is provided between the objective lens and the variable power lens system.
According to a thirteenth aspect of the present invention, there is provided an observation apparatus, which comprises:
a variable power lens system and an imaging lens located on an observation path of the observation optical system extending from an objective lens to an eyepiece, in which:
of the observation optical system, an observation optical system extending from the objective lens to the variable power lens system is an observation path for relaying as parallel light fluxes reflected light from an eye fundus of an operating eye to the variable power lens system;
of the observation optical system, an observation optical system extending from the variable power lens system to the imaging lens is an observation path for relaying as parallel light fluxes the reflected light fluxes obtained through the variable power lens system to the imaging lens; and
the observation optical system includes image receiving means for receiving the reflected light from the eye fundus and displaying an eye fundus image, the image receiving means being connected with an image processing device,
characterized in that the image processing device includes, in order to correct the chromatic aberration caused when optical members are held against the operating eye, chromatic aberration correcting means for correcting chromatic aberration by digitally combining at one point point images that are obtained by separating an image into three colors of R, G, and B on the image receiving means.
According to a fourteenth aspect of the present invention, there is provided an observation apparatus, which comprises a variable power lens system and an imaging lens located on an observation path of the observation optical system extending from an objective lens to an eyepiece, in which:
of the observation optical system, an observation optical system extending from the objective lens to the variable power lens system is an observation path for relaying as parallel light fluxes reflected light from an eye fundus of an operating eye to the variable power lens system; and of the observation optical system, an observation optical system extending from the variable power lens system to the imaging lens is an observation path for relaying as parallel light fluxes the reflected light fluxes obtained through the variable power lens system to the imaging lens; and
eye fundus therapy is performed by using an irradiation optical system for irradiating therapeutic laser light,
characterized in that an astigmatism canceling optical element is provided for canceling astigmatism caused when optical members are held against the operating eye to allow the therapeutic laser light to be irradiated to the eye fundus.